Ground

Ground

Power ground

The following are grounded to grounding point G7:

•	control module pins 25, 47 and 62

•	mass air flow sensor

•	ignition discharge module.

Sensor ground

The following sensors are grounded from control module pins 22 and 70. The two supplies are internally coupled together in the throttle body.

•	Crankshaft position sensor and its screen

•	Manifold absolute pressure sensor

•	Charge air absolute pressure sensor

•	Differential pressure sensor, tank

•	Intake air temperature sensor

•	Temperature sensor, engine coolant

•	Oxygen sensor screens

•	Pedal position sensors

•	Throttle position sensor

Reference ground

Oxygen sensors 1 and 2 are grounded from control module pin 58.

Diagnostics

•	The engine will not start if the power ground is missing and the diagnostic tool will not be able to make contact with the system.

•	The engine will not start if the sensor ground is missing and the throttle will go into limp-home mode. As the two sensor ground outputs are coupled together internally in the throttle body, there will be no symptoms if a break should occur in only one of them.

•	If the reference ground is missing, diagnostic trouble code P0134 will be generated.